We synthetized carbon dots by a pyrolitic method, and studied their photoluminescence in aqueous environment and upon trapping in a solid matrix. To this aim, we devised a facile procedure allowing to embed the dots in amorphous SiO2, without the need of any pre-functionalization of the nanoparticles, and capable of yielding a brightly photoluminescent monolith. Experimental data reveal a remarkable similarity between the emission properties of carbon dots in water and in SiO2, suggesting that the chromophores responsible of the photoluminescence undergo only weak interactions with the environment. Time-resolved photoluminescence data reveal that the typical photoluminescence tunability of these dots mostly arises, in the present case, from the co-existence of two independent emission bands. These two signals have different emission peak positions (2.8-2.9 and 2.2-2.3 eV respectively) and decay lifetimes (7.0 and 9.0 ns respectively), while their intensity ratio is controlled by the excitation wavelength.
Messina, F., Sciortino, L., Buscarino, G., Agnello, S., Gelardi, F., & Cannas, M. (2016). Photoluminescence of Carbon Dots Embedded in a SiO2 Matrix. In Materials Today: Proceedings (Vol. 3, pp. S258–S265). Elsevier Ltd. https://doi.org/10.1016/j.matpr.2016.02.043